Field of the Invention
The present invention relates to the field of electrotechnology and can be used advantageously in rotating electrical machines, for example, electric motors and generators.
The invention relates specifically to an electrical machine, particularly to an electric motor having a stator and a rotor, mounted rotatably around a rotor axis, having a rotor body, whereby permanent magnets are arranged in receptacles of the rotor body.
Description of the Background Art
Such machines can be formed, on the one hand, as an inner rotor with a rotor, located inside, surrounded by a stator and, on the other, as an outer rotor with a hollow cylindrical rotor within whose interior a stator is disposed. Depending on whether this concerns a brushless or a brushed machine, permanent magnets (brushless variant) are provided in the rotor or permanent magnets are provided in the stator and electromagnets in the rotor. Basically, such machines can be optimized in that especially high magnetic field strengths are produced in the magnetic gap between the rotor and stator, as a result of which high torques and power densities can be achieved. In the case of such performance features and corresponding electrical power of the machines, however, it is also increasingly important to allow high operating temperatures, whereby consideration must be given to the fact that the magnetic properties of the magnetic circuit are retained at high operating temperatures, as well as with high active magnetic fields and correspondingly large interfering fields, particularly that there is no demagnetization of the permanent magnets by interfering fields. For this purpose, certain coercive field strengths of the employed materials are necessary, at least in the region of the permanent magnets, exposed to the increased interference fields. On the other hand, high remanence values are also desirable, because these are decisive factors for the size of the achievable magnetic flux in the magnetic circuit.
Ultimately, suitable material values with optimally matched geometries should be combined in the construction of the rotor and stator.